1. Field of the Invention
The present invention relates to a light intercepting device in a lens barrel of a camera which as a photographing lens system and a separate finder optical system.
2. Description of Related Art
In a conventional compact camera having a photographing lens system and a finder optical system separate from the photographing lens system, a lens frame which supports a group of focusing lenses is screw-engaged in a center portion of a control unit which controls the focus and exposure. The lens frame is engaged by an operation pin of the control unit to move together in a circumferential direction. The operation pin is rotated by an angular displacement corresponding to an object distance signal which is detected by an object distance measuring device to rotate the lens frame thereby to move the focusing lens group to a focal position. The control unit has a shutter sector which is opened and closed in accordance with a brightness signal detected by a brightness detecting device.
Although the basic arrangement mentioned above has been directed to a camera having a fixed focal length lens, the same is true in a zoom lens camera or a camera having two focal lengths (multiple focal lengths). However, the axial displacement of the control unit which supports the focusing lens group in a zoom lens camera or a two-focus camera is larger than that in the fixed focus camera. This makes it difficult to completely intercept light within the periphery of the control unit, particularly in a zoom lens camera or a two-focal lengths camera. Namely, a large axial displacement of the control unit which carries the focusing lens group takes place when the focal length varies. On the other hand, the control unit must be electrically connected to the object distance measuring device and the brightness detecting device on the camera body. The electrical connection is usually made by a flexible printed circuit board (FPC board) which flexibly runs through and around the control unit. To this end, there are gaps in the periphery of the control unit, through which the FPC board extends. The gaps, however, make it difficult to completely intercept light.
Furthermore, a conventional light intercepting device usually includes a slide member for intercepting light, such as a light intercepting ring which, however, causes slide or frictional resistance. The large slide resistance increases the drive force or torque necessary for driving the control unit and the zooming operation, etc.